Bug 577958: use "Delete" label and icon in launch view

Since the launch config is really deleted and not just removed from the
view, the icon and label should match the normale delete action.

Change-Id: I63d411da46b353bccef4035560cd59f88d8f42c6
Signed-off-by: Michael Keppler <michael.keppler@gmx.de>
Reviewed-on: https://git.eclipse.org/r/c/platform/eclipse.platform.debug/+/189131
Tested-by: Platform Bot <platform-bot@eclipse.org>
Reviewed-by: Markus Duft <markus.duft@ssi-schaefer.com>